Status of Low-Background Infrared Calibration Facility at NIST

Transcription

1 Status of Low-Background Infrared Calibration Facility at NIST Simon G. Kaplan #, Solomon I. Woods #, Julia Scherschligt #, Joseph P. Rice #, Adriaan C. Carter *, and Timothy M. Jung * # National Institute of Standards and Technology * Jung Research and Development 1 Calcon August 11, 2014

2 Outline Introduction to Low Background Infrared (LBIR) facility IR test chamber calibrations with NIST Missile Defense Transfer Radiometer (MDXR) Brief functional mode and calibration review Results from calibration of user chambers over 5 years New IR sensor development pw ACR, Si:As BIB trap detector, carbon nanotube ACR New IR source development fluid bath blackbody Conclusions 2

3 NIST radiometric calibration support for missile defense ground test facilities Radiometric calibration of infrared seekers on missile kill vehicles (KVs) is essential to ensure that the devices have the required sensitivity, spectral discrimination, and reliability to perform their mission The KV manufacturers and others maintain a suite of lowbackground vacuum infrared test chambers for radiometric and spectral calibration of the sensors, as well as hardware-in-the-loop testing of discrimination/tracking performance 3 Since the 1990 s, the NIST LBIR facility has provided calibration support for these test chambers: - traceability to national primary standard for infrared power - characterization of chamber performance, e.g., polarization, wavelength calibration, filter transmittance, etc.

4 NIST radiometric calibration support for missile defense ground test facilities Spiral development program for missile defense results in continually more demanding uncertainty requirements for radiometric calibration and sensor spectral discrimination capability The LBIR facility continues to improve its primary scale for lower infrared irradiance levels and methods for transferring the scale to its customers Current LBIR missile defense customers: Raytheon Missile Systems, Tucson, AZ (AB, GMD) Arnold Engineering Development Center, Tullahoma, TN (GMD) Johns Hopkins Applied Physics Laboratory, Laurel, MD (AB) 4

5 Low-Background Infrared Facility (LBIR) On-site characterization of Raytheon EKV test chamber Calibration of EKV blackbody in LBIR facility 5 LBIR facility located at NIST Gaithersburg, MD Range of Test Parameters Blackbody calibrations with absolute cryogenic radiometer (ACR) 1nW W power range Uncertainty currently 1 sigma 100mK On-site measurements with portable transfer radiometer - BXR since 2001; MDXR 2009 Irradiance levels: to 10-9 watts/cm 2 Spectral range 2-30 m with filters, FTS

6 Low-background IR test chambers calibration considerations Mirror Collimated Infrared Beam (used for sensor calibration and testing) Sensor Mirror Reflected throughput Effective focal length Diffraction Aberrations Adsorbed gases Scattering Stray light Other Possible Optics Transmittance or reflectance Alignment, vignetting Polarization Blackbody Infrared Source Assembly Cavity temperature, T Emissivity e(l,t) Aperture area, A Filter transmittance, t Emission from aperture, chopper, filter 6 Cryogenic vacuum chamber

7 7 Capability BXR ( ) MDXR (2009-present) spectral definition filter-based 2-14 um Si:As BIB detector entrance aperture 7 cm diameter 7 cm diameter Fourier transform spectrometer (FTS) and filters 3-30 um Si:As BIB detector stability assessment Limited ACR and blackbody (200 K to 400 K) polarization capability rotatable linear polarizer rotatable and fixed linear polarizers calibration modes irradiance, polarimeter irradiance, radiance, polarimeter, FTS, absolute power radiometer base 20 K 20 K temperature detector base temperature 9 K 2 K radiometric uncertainty (k=1) NIST LBIR transfer radiometers 3.5 % filter radiometer (FR) 2.5 % FTS 1.3 % ACR > 0.5 % noise floor 3 x10-16 W/cm 2 / m FR 1.5x10-16 W/cm 2 / m FTS 1.3x10-13 W/cm 2 / m in a 4 cm -1 spectral interval ACR 3.0x10-12 W/cm 2

8 8 MDXR attached to LBIR 10 centimeter collimator chamber

9 MDXR beam path detector side BIB detector(s) Tertiary paraboloid Filter wheels (spectral and polarization) Translating periscope ACR Cryo-FTS 3-axis stage Secondary paraboloid Variable field stop wheel 9

10 MDXR filter mode calibration factors The MDXR filter mode calibration is done on a band by band basis by viewing the 10CC output with both the FR and ACR. The filter set by which the MDXR is calibrated is the exact same set that is used to calibrate the customer s IR test chambers. The horizontal extent of the lines represent the approximate spectral width of the filter bands used for calibration activities. 10

11 Radiometric calibration of cryogenic FTS mode Using irradiance from internal MDXR blackbody viewed with internal 7 cm collimator Primary paraboloid Collimator Blackbody source 1.0 mm aperture K Defining aperture (7 cm dia) 11 External source SRF ( ) S Planck S ( ) Internal source (with collimator) measured geom ( ) C R Diff mirror ( ) 2

12 Measured/Model Measured/Model Comparison of FTS and FR measurements of user chambers Compare FR to CFTS Roxanne Ap 14 Feb ISSCAT-1 TSM2 Aperture 7 April K 400 K 500 K 600 K 800 K K 340 K 400 K 500 K Wavelength (um) Wavelength (um) 12 FTS and FR results agree within combined (k=1) uncertainties

13 Measured/Model MDXR results for various chambers over 5 years 1.2 MDXR FR measurements user source temperature = 400 K Wavelength ( m) 13 Majority of measurements fall within ± 5 % of the chamber model predicted spectral irradiance

14 MDXR results for one chamber over three years Majority of measurements fall within ± 1 % over successive years of measurements on same (unchanged) chamber. ACR results show < 0.2 % change 14

15 FTS diagnostic results for IR source assemblies Effect of filter heating with source at 800 K Effect of aperture heating with source at 800 K Apparent contribution of emission from filter heating at long wavelength Successive spectra at 10 sec intervals after opening shutter => aperture heated to 135 K (22 um peak) within several minutes 15

16 New sensors being developed for infrared power primary scale realization pw ACR Si:As BIB Trap Detector Carbon nanotube radiometer - Reduced receiver size and improved thermometry - Goal ~10 fw noise floor - RF shielded, 2 K - Compare to pw ACR primary scale from 2 m to 30 m - Transfer to other radiometers - High speed ACR (~ 1 khz) - Range of possible uses - preceding talk by Solomon Woods et al. 16

17 Temperature Controlled Fluid Bath Large Aperture Fluid Bath Blackbody 200 K to 400 K 12 cm Entrance Aperture 60 cm Deep Cavity Expected benefits from Water Bath Blackbody Radiance calibration capability for BXR and MDXR Validate methodology used for the calibration of blackbodies by the ACR Available for loan to LBIR User community for on-site calibration activities All parts fabricated; assembly and testing underway Measurements of cavity emissivity using NIST CHILR facility show e = at 10.6 m and e = at 4 m (see poster by Zinan Jeng et al.) 17

18 Conclusions and future work MDXR has been successfully deployed to calibrate users cryogenic vacuum infrared test chambers since 2009 Demonstrated ability to track chamber radiometric performance within 1 % and provide spectral characterization with 1 cm -1 resolution New absolute sensors being developed for direct traceability to watt at lower power levels or in wider application range New fluid bath blackbody for end-to-end testing of LBIR blackbody calibrations being tested Planning underway with user community for NIST support/development of user-owned radiometers for chamber calibrations 18